xref: /freebsd/sys/powerpc/powermac/vcoregpio.c (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2009 Nathan Whitehorn
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  *
28  */
29 
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/module.h>
33 #include <sys/bus.h>
34 #include <sys/conf.h>
35 #include <sys/cpu.h>
36 #include <sys/eventhandler.h>
37 #include <sys/kernel.h>
38 #include <sys/sysctl.h>
39 
40 #include <dev/ofw/ofw_bus.h>
41 #include <dev/ofw/openfirm.h>
42 
43 #include <powerpc/powermac/macgpiovar.h>
44 
45 static int	vcoregpio_probe(device_t);
46 static int	vcoregpio_attach(device_t);
47 static void	vcoregpio_pre_change(device_t, const struct cf_level *level);
48 static void	vcoregpio_post_change(device_t, const struct cf_level *level);
49 
50 static device_method_t  vcoregpio_methods[] = {
51 	/* Device interface */
52 	DEVMETHOD(device_probe,		vcoregpio_probe),
53 	DEVMETHOD(device_attach,	vcoregpio_attach),
54 	{ 0, 0 },
55 };
56 
57 static driver_t vcoregpio_driver = {
58 	"vcoregpio",
59 	vcoregpio_methods,
60 	0
61 };
62 
63 DRIVER_MODULE(vcoregpio, macgpio, vcoregpio_driver, 0, 0);
64 
65 static int
66 vcoregpio_probe(device_t dev)
67 {
68 	const char *name = ofw_bus_get_name(dev);
69 
70 	if (strcmp(name, "cpu-vcore-select") != 0)
71 		return (ENXIO);
72 
73 	device_set_desc(dev, "CPU Core Voltage Control");
74 	return (0);
75 }
76 
77 static int
78 vcoregpio_attach(device_t dev)
79 {
80 	EVENTHANDLER_REGISTER(cpufreq_pre_change, vcoregpio_pre_change, dev,
81 	    EVENTHANDLER_PRI_ANY);
82 	EVENTHANDLER_REGISTER(cpufreq_post_change, vcoregpio_post_change, dev,
83 	    EVENTHANDLER_PRI_ANY);
84 
85 	return (0);
86 }
87 
88 static void
89 vcoregpio_pre_change(device_t dev, const struct cf_level *level)
90 {
91 	if (level->rel_set[0].freq == 10000 /* max */) {
92 		/*
93 		 * Make sure the CPU voltage is raised before we raise
94 		 * the clock.
95 		 */
96 		macgpio_write(dev, GPIO_DDR_OUTPUT | 1);
97 		DELAY(1000);
98 	}
99 }
100 
101 static void
102 vcoregpio_post_change(device_t dev, const struct cf_level *level)
103 {
104 	if (level->rel_set[0].freq < 10000 /* max */) {
105 		DELAY(1000);
106 		/* We are safe to reduce CPU voltage now */
107 		macgpio_write(dev, GPIO_DDR_OUTPUT | 0);
108 	}
109 }
110